Hydraulic power apparatus



NV. 10, 1936. -v E MOODY 2,060,101

HYDRAULIC POWER APPARATUS Filed Ney.' 22, 1955 4 sheets-sheet 1 Nov. 10, 1936. 1 F. MOODY 2,060,101

HYDRAULIC POWER APPARATUS 4 Sheets-Sheet 2 Filed Nov. 22, 1955 Nov. 10, 1936. F. MOODY HYDRAULIC POWER APPARATUS Filed NOV. 22, 1933 4 Sheets-Sheet 3 Nov. 10, 1936. L. F. MOODY HYDRAULIC POWER APPARATUS Filed Nov. 22, 1933 4 Sheets-Sheet 4 'Ill' O I,

Patented Nov. l0, 1936 UNITED STATES PATENT OFFICE 2,060,101 HYDRAULIC POIWER APPARATUS Lewis Ferry Moody, Princeton, N. J.

Application November 22,

1933, serial No. 699,230

18 Claims. (Cl. 253-117) This invention relates to hydraulic turbines of propeller turbines, made relatively large in diameter as required by the mechanical design necessary for the blade In propeller turbines of the admay be employed.

Other objects and advantages of the invention will be apparent from the following description and claims.

In general the eliminating the such a space when the pressure approaches the barometric limit, namely, the collapsing or explosion of the vapor lled cavity and resulting Water hammer, vibration and instability of ilow. The tendency toward the formation of a cavity in the central region of the draft tube is accentua-ted in turbines of high specic speed, including both propeller and high-speed Francis turbines, due to the whirl components of the discharge velocity from the runner. When a whirlbine unit and powerhouse.

The invention is illustrated by a number of embodiments shown in the following drawings:

powerhouse on line I-I of Fig. 2;-

Fig. 2 is a horizontal section of the draft tube of Fig. 1 on line 2 2 of Fig. 1;

Fig. 3 is a sectional elevation of a fixed-blade propeller turbine, the draft tube being identical with that of Fig. 1 except for a reduction in diameter of runner hub;

Fig. 4 is a vertical transverse section of the turbine of Fig. 3 on line 4 4 of Fig. 3 looking upstream. Except for the change in diameter of hub and cylinder, this view also represents a corresponding section of the draft tube of Fig. 1;

Figs. 5 and 6 are corresponding longitudinal and transverse vertical sections of a modified tube; and

Fig. 7 is the corresponding horizontal section on line 1-1 of Fig. 5. In this modification the longitudinal pier is reduced in thickness below the diameter of the hub;

Fig. 8 is a horizontal section of draft tube similar in longitudinal section to Figs. 1 and 3 but having a curvature where it joins the cylindrical portionas shown in Fig. 8;

Fig. 9 is a longitudinal section of a draft tube similar to those of Figs. 1 to 3 but with the central pier extended on the upstream side of the cylinder to the upstream wall of the tube;

Fig. 10 is a transverse section of the tube of Fig. 9 on line I0--I 0 of Fig. 9 looking downstream;

Fig. 11 shows in longitudinal section a modification of Figs. 1 to 4, showing the addition of a deflecting guide plate or baffle;

Fig. 11a shows the application of my invention to a Francis runner;

Fig. l2 is another modification in which the supported laterally by diffusion vanes below the runner, the longitudinal pier extending from the cylinder being omitted;

Fig. 13 is a further modification in which the lower part of the cylinder is omitted and a short stationary cylinder and cone element below the runner hub is supported by diffusion vanes;

Fig. 14 is a still further modification in which the lower part of the cylinder is supported by a longitudinal pier and the upper part by diffusion vanes. The figure also shows a guiding plate or baffle which can be added when desirable.

In Fig. 1 the water enters the turbine through the casing I, here of volute form, passing through the stay vanes 2, wicket gates 3, transition space 4, and runner 5. The blades of the runner are rotatably adjustable in the hub 6, being actuated by the servo-motor 'I mounted in the shaft. water passes from the runner into an elbow draft tube 8 which has a gradually directed horizontal discharge portion 8a discharging into the tail race 9. Below the runner is a central core Il, here shown as of cylindrical shape, registering with the runner hub in contour. Suitable clearance is provided between the stationary core and the revolving hub. The core or cylinder will usually be constructed of reinforced concrete, and the upper part may be provided with a cast or plate metal covering as shown in Moody Patent No. 1,683,567 and Taylor Patent No. 1,681,712. Within the horizontal discharge portion of the draft tube is a vertical longitudinal pier I2 which is continued upstream into the elbow portion of the tube, joining and merging with the central core or cylinder II which forms an upstream nose or rounded entrance edge for the pier.

The same general form of draft tube is shown in Figs. 2 to 4, slightly modified to suit the smaller hub of a fixed blade propeller runner. The same symbols have been repeated in these figures. The upper edge of the longitudinal pier where the water first meets it is curved as shown at I3 in Fig. 4 to suit the oblique direction of flow due to the whirl components of the discharge velocity from the runne It will be understood that the same general formation may be used with Francis runners R as shown in Fig. 11a., and the various draft tube features shown in all the figures are not limited to one particular form of runner.

The longitudinal pier in the elbow portion of the draft tube serves three purposes. It provides a continuation of the central core or cylinder in the downstream direction so that the flow passing around the outer portion of the elbow and flowing laterally past the lower part of the cylinder on its way toward the tailrace will not form a void or cavity within the stream on the downstream side of the cylinder. The pier also provides a strong lateral support for the cylinder which is a structural requirement and furnishes valuable support for the superposed portion of the powerhouse. The pier with its properly curved upward portion serves another hydraulic function namely that of a guide blade to control the whirl components and gradually to reduce their amount, thus straightening and smoothing out the flow while it passes around the elbow and eliminating counter flows and interferences.

In some cases, particularly with adjustableblade runners having large hubs as required by the blade adjusting mechanism within them, it may not be desirable, structurally or hydraulically, to maintain the cylindrical core in the draft tube at the full diameter of the hub. Figs. 5 and 6 show a formation in which the core is gradually tapered downward to a smaller diameter. It may also in some cases be desired to reduce the thickness or the longitudinal pier, when a greater thickness is not needed for strength, below that of the cylinder. This modification is shown in Fig. 7 which is a horizontal section corresponding to Figs. 5 and 6. Here the cylindrical core forms a nose or rounded entrance edge for the pier and is curved on a gradual taper into the contour of the thinner pier.

When desired, the discharge portion of the draft tube may be offset from the axis of the turbine to suit the whirl components of the ow entering the tube. When this is done, the longitudinal pier may be offset and curved into the cylinder as shown in Fig. 8.

To accentuate the guiding function of the longitudinal pier and to provide additional lateral support for the cylinder, it is in many cases desirable to continue the pier to the upstream wall of the draft tube, as shown in Figs. 9 and l0. I-lere, as indicated by the solid and dotted lines I4 and I5 in Fig. 10, the entrance edges of the pier must be curved in opposite directions to conform to the angle of the whirling flow.

In Fig. 1l is shown a further modification, the addition of a transverse guide plate or baffle I6. This is to guide the flow while passing around the elbow and to avoid cross currents and distorted velocity distribution and to discharge the water smoothly and with nearly uniform velocity into the horizontal discharge section of the tube. It permits more rapid and efficient deceleration of the curving flow. It also furnishes additional structural support for the cylinder and pier in a lateral direction. In Fig. l1 the baille is shown as a steel plate (either plate steel or casting) inserted into the concrete pier and cylinder. If desired, it may be made thicker and formed of reinforced concrete.

It extends horizontally on both sides of the pier, its ends being imbedded in the concrete side walls of the draft tube. Instead of placing the curved guide plate or baille on or near the centerline of the passage, it is preferable, as shown in Fig. l1, for hydraulic reasons to place it slightly higher and slightly downstream from the centerline of the passage so that it will more efficiently guide the more rapid flow which occurs along the inside surface of the bend and upper surface of the passage. This may be understood when it is considered that the velocity of flow tends to increase toward the inner surface of the bend because the centrifugal forces of the curving stream elements increase the pressure head at the outer wall of the bend and reduce it at the inner wall, and the velocity head increases by the amount that the pressure head is reduced. Consequently the velocities are highest near the inner wall of the bend, greater quantities of ilow will pass through the innermost half of the passage than through the outermost half, and the central flow line will be displaced inwardly from the curved centerline of the passage. Furthermore, since the innermost portion of the stream is flowing at higher is a strong tendency for the ow to depart from the inner surface of the bend, leaving regions of backward ow and turbulence. For these reasons section ON that bi is equal to or slightly less than a mean proportional to a and c; that is b b` c or bw/ac vanes are spaced from the runner to provide a free transition space I9, and are curved slightly to conform to, and to produce, a gradual reduction of whirl components of velocity and Obliquity of flow.

Fig. 13 shows a further modification in which piece 2|, supported by guide and stay vanes from tube. It will be understood that for simplicity the draft tubes in the various figures have been shown as if constructed entirely noted ythat when guide Vanes of the type shown in Figs. 12 to 14 are used with adjustable-blade runners, somewhat less curvature and inclination are usually needed for the guide vanes, since the whirl components are somewhat reduced.

By the use of the various features of the invention described herein the formation of voids or cavities Within the 2. In a vertical shaft a runner, an elbow draft tube having a discharge than to the outside thereof substantially throughout its length.

4. In a vertical shaft a runner, an elbow draft tube having a discharge runner to provide an unobstructed transition space between the runner and upper edge of said pier.

5. In a vertical shaft hydraulic turbine having a runner, a draft tube and discharge passage therefor discharging the iiow downstream into the tailrace, said draft tube including a vertical central pier extending downstream into said discharge passage and upstream as far as the runner axis and terminating at its upstream end in a rounded nose, and having a horizontal thickness substantially equal to that of the diameter of the runner hub so as to form a continuation thereof; said pier extending upward from the bottom surface of the draft tube and terminating in an upper substantially horizontal edge at a point below the runner to provide an unobstructed transition space between the runner and upper edge of said pier, said upper edge being rounded and tapered to receive the flow without disturbance.

6. In a vertical shaft hydraulic turbine having a runner, a draft tube and discharge passage therefor discharging the flow downstream into the tailrace, said draft tube including a vertical central pier extending downstream into said discharge passage and upstream as far as the runner axis and terminating at its upstream end in a rounded nose, and having a horizontal thickness substantially the same as that of the diameter of the runner hub so as to form a continuation thereof; said pier extending upward from the bottom surface of the draft tube and terminating in an upper substantially horizontal edge at a point below the runner to provide an unobstructed transition space between the runner and upper edge of said pier, said upper edge being rounded and tapered to receive the ow without disturbance and said pier in its portion immediately below the runner hub being formed as a surface of revolution continuous in contour with the surface of the hub.

'7. In a vertical shaft hydraulic turbine having a runner, a draft tube and discharge passage therefor discharging the iiow downstream into the tailrace, said draft tube including a vertical central pier extending downstream to the end of said discharge passage and upstream as far as the runner axis and terminating at its upstream end in a rounded nose, and having a thickness not greater than the diameter of the runner hub; said pier extending upward from the bottom surface of the draft tube and terminating in an upper substantially lateral edge at a point below the runner to provide an unobstructed transition space between the runner and said upper edge of said pier, said upper edge being rounded and tapered to receive the flow without disturbance.

8. In a hydraulic turbine having a runner, a draft tube of generally elbow formation turning the flow and discharging it substantially perpensaid draft tube including a central pier lying in the central plane of the elbow and extending from the outer end of the discharge passage upstream at least as far axis and also extending from the top of the discharge passage, and a thickness substantially equal to that of the runner hub diameter to form a continuation thereof.

9. In a vertical shaft hydraulic turbine having a runner, a draft tube and discharge passage therefor discharging the flow downstream into the tailrace, said draft tube including a vertical central pier extending downstream into said discharge passage and upstream as far as the runner axis and terminating at its upstream end in a rounded nose, and having a horizontal thickness not greater than the diameter of the runner hub; said pier extending upward from the bottom draft tube and terminating in an upper lateral edge at a point below the runner to provide an unobstructed transition space between the runner and said upper edge of said pier, said upper edge being tapered and rounded with greater taper on one side than on the other to conform to a flow having a whirl component in the direction of runner rotation.

10. In a vertical shaft hydraulic turbine having an adjustable-blade propeller type runner, an elbow draft tube and discharge passage therefor discharging the flow downstream into the tailrace, said draft tube including a vertical central downstream into said discharge passage and upstream as far as the runner axis and terminating at its upstream end in a rounded nose, and having a horizontal thickness substantially equal to that of the diameter of the runner hub to form a continuation thereof; said pier extending upward from the bottom to the top surfaces of the draft tube and terminating in a lateral edge at a point below the runner to provide an unobstructed transition Space between the runner and upper edge of said pier.

1l. In a vertical shaft hydraulic turbine having a runner, an elbow draft tube and discharge passage therefor discharging the flow downstream into the tailrace, said draft tube including a vertical central pier extending downstream into said discharge passage and upstream to the upstream wall of the draft tube, and having a horizontal thickness not greater than the diameter of the runner hub; said pier extending upward from the bottom to the top surfaces of the draft tube and terminating in a lateral edge at a point below the runner to provide an unobstructed transition space between the runner and upper edge of said pier, and said pier in its portion immediately below the runner hub being formed as a surface of revolution continuous in contour with the surface of the hub.

l2. In a hydraulic turbine or pump having a propeller type runner, a draft tube or diffuser and discharge passage therefor discharging the flow substantially perpendicularly to the runner axis, said draft tube or diffuser containing a central partition lying in the central plane of the discharge passage and extending from the bottom to the top surfaces thereof and also extending upstream at least as far as the runner axis, said partition having a thickness substantially equal to that of the runner hub diameter so as to form a continuation thereof.

13. In a vertical shaft hydraulic turbine having a runner, an elbow draft tube having a discharge passage for discharging the flow downstream into the tailrace, said draft tube including a stationary central core of diameter not exceeding that of the runner hub, said core extending from and coaxially of said runner on the discharge side thereof, and a vertical central pier extending laterally from said core into the discharge passage in a downstream direction toward the tailrace and having side surfaces merging face of said core, and a transverse partition curving from substantially vertical to horizontal in the discharge passage and nearer to the inside band of the draft tube elbow than to the outside thereof substantially throughout its length.

into the suI- 14. In a rotary hydraulic machine having a runner, a velocity decelerating passage of generally elbow formation turning the ow after discharge from the runner and discharging the iiow substantially perpendicular to the runner axis, said decelerating passage including a central pier lying in the central plane of the elbow, and a partition perpendicular to said pier curving from a direction substantially parallel to the runner axis at its entrance end to a substantially perpendicular direction at its discharge end and located substantially throughout its length nearer to the inside and downstream surface of the elbow than to the outer and upstream surface, said partition being so located in a section transverse to the centerline of the passage that its distance from the center of curvature of the centerline is not greater than the mean proportional of the distances of said center of curvature from the inner and outer surfaces of the passage.

15. In a hydraulic turbine having a runner, a draft tube of generally elbow formation turning the flow and discharging it substantially perpendicularly to the runner axis, said draft tube including a central pier lying in the central plane of the elbow extending from the discharge end of the draft tube upstream at least as far as the runner axis, and having in the portion near the axis a thickness not greater than the runner hub diameter, and a single substantially central horizontal partition curving from substantially vertical to substantially horizontal and having its downstream portion, substantially throughout its length, offset from the centerline of the draft tube toward the upper and inner surface of the elbow.

16. In a hydraulic turbine having a runner, a draft tube of generally elbow formation turning the flow and discharging it substantially perpendicularly to the runner axis, said draft tube S including a horizontal partition curving from substantially vertical at its entrance end to substantially horizontal at its discharge end and having said entrance end located substantially in the centerline of the draft tube and having said discharge end located, substantially throughout its length, nearer to the upper and inner surface of the elbow than to the lower and outer surface.

17. In a rotary hydraulicl machine having a runner, a velocity decelerating passage of generally elbow formation turning the flow after discharge from the runner and discharging the flow substantially perpendicular to the runner axis, said decelerating passage including a central pier lying in the central plane of the elbow, and a single partition perpendicular to' said pier curving from a direction substantially parallel to the runner axis at its entrance end to a substantially perpendicular direction at its discharge end land having its discharge end substantially throughout its length, oiset from the centerline of the passage toward the runner.

18. In a hydraulic turbine having a runner, a draft tube of generally elbow formation turning the flow and discharging it substantially perpendicularly to the runner axis, said draft tube including a partition generated by straight lines perpendicular to the plane of the elbow and said partition curving from a substantially axial direction at its entrance end to a direction substantially perpendicular tothe turbine axis at its discharge end and having said entrance end located substantially in the center line of the draft tube, the remainder of said partition deviating from the central line of the elboW passage by progressively increasing amounts from its entrance to its discharge end, said deviation being in a direction toward the center of curvature of the elbow.

LEWIS FERRY MOODY. 

